A need has been recognized for many years for an artificial tooth implant to successfully and permanently replace extracted or otherwise lost natural teeth in humans. It is understood that some experimentation in this area has been conducted on animals and humans utilizing plastic tooth implants with varying degrees of success. There is also some patented prior art relating to artificial tooth structures capable of being mechanically anchored in the natural tooth socket of humans with the assistance of bone-engaging threaded pins and the like. Some examples of the patented prior art are U.S. Pat. Nos. 448,745; 2,609,604; 3,435,526; and 2,347,567.
Generally speaking, prior art proposals along this line have not been widely adopted and have not been technically successful due to various factors existing in the human body and certain limitations inherent in the materials used for artificial tooth transplants.
Therefore, the object of this invention is to provide a completely successful artificial human tooth implant and method of producing which utilizes unique materials for the implant which are compatible with the normal growth of human tissue and bone structure so that the implant will become naturally anchored in the gum socket after installation, which may include initially an anchorage screw or pin for the underlying alveolar bone. More particularly, it has been discovered that certain porous metals and ceramics which can be molded by known techniques possess the physical characteristics which allow and facilitate successful periodontal fiber attachment and natural bone support without any apparent rejection by the human body. It appears that the periodontal fibers may penetrate deeply into the pores of the ceramic or like material for permanent natural anchorage of the prosthesis.
While it is contemplated ultimately that the implant may embody an exact replica of the whole tooth formed of suitable powdered metal, ceramic, pyrolytic carbon or the like with the porosity localized in the root portion, the invention at present is intended to be practiced in terms of a porous material replica of the root portion of the tooth topped by a porcelain cap or the like applied by conventional dental techniques.
The essential method embodying the invention consists of first extracting the natural tooth and immediately thereafter forming an exact flexible or rigid mold of the tooth, or one that is slightly oversize to compensate for shrinkage during casting, sintering or pressing. Next, the mold cavity which may or may not contain cast, wrought, or sintered shapes to which the powder will ultimately be bonded, is filled with an acceptable dental alloy, titanium, or a titanium alloy in the form of a powdered metal, followed by pressing, if required, and sintering. In the case of ceramics, the material is packed in a rubber mold and pressed and sintered or placed in a ceramic mold and vibrated with direct sintering. Following the formation of the molded replica of the tooth, it can be coated with porous alumina, titania or dental porcelain, and then placed directly in the natural tooth socket. By using narrowly sized fractions of metal, ceramic, or pyrolytic carbon, spherical or angular powder and combining these fractions so that binary, tertiary or quatinary mixtures of particles whose diameters are such that each smaller spherical or angular particle is 1/7 the diameter of the next larger particle diameter, high density powder mixtures with densities in excess of 80 percent prior to sintering can be achieved. For example, in a binary system, spheres of diameter D.sub.1 would be mixed with spheres of diameter D.sub.2 =1/7 D.sub.1. The high density powder mixes achieved exhibit very low sintered shrinkages.
The implant is preferably drilled and tapped and provided with a threaded pin extending below the tip of the root or roots into the underlying alveolar bone. This serves to stabilize the implant until the periodontal membrane and/or natural bone migrates into the surface pores of the implant.
The many advantages of the invention over the prior art will appear during the course of the following description taken in connection with the accompanying drawings which form a part of this application.